My earlier patent application Ser. No. 910,809 filed 5/30/78 discloses unloading recesses on a control body or control pintle, which carries a rotor. The teaching and aim of the said application is, to force the rotor to float eccentrically relatively to the axis of the control pintle in order to bring the inner face of the rotor closer to the outer face of the control pintle in the high-pressure zone adjacent the high pressure control port.
The present invention now discovers, that similar means can be utilized to make the rotor float either centrically, eccentrically or float with a pre-determined limted eccentricity around the control pintle, when the unloading recesses are respectively located. Means to supply pressure fluid to actuate hydrodynamic pressure fields at partially eccentric or eccentric rotation of the rotor can be added.
The invention thereby obtains reduced leakage or reduced friction and makes it possible to obtain any desired centric, eccentric or partial eccentric running of the rotor relatively to the control-pintle.